AND TREVIORPHISM. 281 



observe during four years many seedlings, raised from sev- 

 eral illegitimate unions. The chief result is that these 

 legitimate plants, as they may be called, are not fully 

 fertile. It is possible to raise from dimorphic species, both, 

 long-styled and short-styled illegitimate plants, and from 

 trimorphic plants all three illegitimate forms. These can 

 then be properly united in a legitimate manner. When this 

 is done, there is no apparent reason why they should not 

 yield as many seeds as did their parents when legitimately 

 fertilized. But such is not the case. They are all infertile, 

 in various degrees; some being so utterly and incurably 

 sterile that they did not yield during four seasons a single 

 seed or even seed-capsule. The sterility of these illegiti- 

 mate plants, when united with each other in a legitimate 

 manner, may be strictly compared with that of hybrids when 

 crossed inter se. If, on the other hand, a hybrid is crossed 

 with either pure parent-species, the sterility is usually much 

 lessened and so it is when an illegitimate plant is fertilized 

 by a legitimate plant. In the same manner as the sterility 

 of hybrids does not always run parallel with the difficulty 

 of making the first cross between the two parent-species, so> 

 that sterility of certain illegitimate plants was unusually 

 great, while the sterility of the union from which they were 

 derived was by no means great. With hybrids raised from 

 the same seed-capsule the degree of sterility is innately 

 variable, so it is in a marked manner with illegitimate 

 plants. Lastly, many hybrids are profuse and persistent 

 flowerers, while other and more sterile hybrids produce few 

 flowers, and are weak, miserable dwarfs ; exactly similar 

 cases occur with the illegitimate offspring of various dimor- 

 phic and trimorphic plants. 



Altogether there is the closest identity in character and 

 behavior between illegitimate plants and hybrids. It is 

 hardly an exaggeration to maintain that illegitimate plants 

 are hybrids, produced within the limits of the same species 

 by the improper union of certain forms, while ordinary 

 hybrids are produced from an improper union between so- 

 called distinct species. We have also already seen that 

 there is the closest similarity in all respects between first 

 illegitimate unions and first crosses between distinct species. 

 This will perhaps be made more fully apparent by an illus- 

 tration; we may suppose that a botanist found two well- 

 marked varieties (and such occur) of the long-styled form of 

 the trimorphic Lythrum salicaria, and that he determined to 



